Can't edit Clan "Culture" fields. Help?

I am the "founder" of the DestinyBungieOrg PSN clan (one of three platform-specific clans related to the longstanding DBO (destiny.bungie.org) fan community).
I have been unable to edit the Clan "Culture" fields since before D2 launched. Every time I try to edit the info (specifically, the "motto" as that is the only part that is empty) - I am given an error that says, "The provided clan name or clan tag is not acceptable, please choose another."
Obviously, this cannot be correct... I'm not trying to change the clan name or clan tag -- both of which are obviously acceptable anyway since they were allowed in the first place, and are also nearly identical to our other two clans (DestinyBungieOrg XBL and DestinyBungieOrg PC, all three of which have the clan tag "DBO"). We are not having the same error when we change the clan culture on the other two clans -- so we're completely baffled as to why the DestinyBungieOrg PSN clan is an outlier.
As a lot of clan-related features were a bit wonky at first, we were hoping that this was one of the kinks that would be worked out naturally with the tweaks soon after launch and the clan migration process was resolved. However, I am still getting this error and am completely unable to add a clan motto. The urgency to get this resolved has increased recently as we have become aware that the lack of this field is preventing us from being able to host "guided games".
Any help would be greatly appreciated!

Because clan strings can appear in game, they are subject to to additional validation by our platform partners. Unfortunately, due to a bug in bungie.net, the wrong error message is being returned so you can't see what is being flagged by the validator. While that bug will be fixed soon, your particular problem should be solved if you remove the "bungie.net" from your mission statement when you are attempting to add your motto.